1: dirt - mud - water - debris - detrius of war
this can impede or prevent a firearm from operating
the super tight tolerances made this issue pronounced

2: ammo age and production standards
ammo for the british empire (.303) was made on several continents over a 60+ year timespan
it was not made to exacting tolerances and was stored under some dubious conditions
the super tight tolerances made this issue pronounced"

Once again, the dirt and mud problem arose with the Model 1910 which was, as noted, a whole different rifle from the original poster's Model 1905. The Model 1905 (Mk II) was never used in wartime; it was too late for the Boer war and too early for WWI. The Model 1905's problems cropped up in testing and training, not in the trenches of Europe.

The Model 1910 did have dirt and mud problems, but problems with ammunition made over a 60 year period on several continents was not one of them. For one thing, forty of those years had not come yet, and the ammunition used by the British and Canadians in WWI was made in England and the U.S.

In my parts bin is a 1905 Ross action damaged when the bolt blew out of it. A gunsmith I know with experience with the Ross examined it and said that it had the characteristics he had seen before when Ross rifles were fired with improperly locked bolts. The back of the bolt looks like it hit something after being forcefully ejected. From the history of the Ross, it is known that the RNWMP rejected the 1905 Ross because of this very problem.

Can you post some pictures of that action? I think we would all like to see what happens when the bolt blows out. My experiment proved to me that a 1910 can be fired with an unlocked bolt, but I used a primed case. I saw no reason to destroy the rifle when I knew what would happen.

Here you are. The bolt will not go all the way back into the damaged action. Note the bulged out section and cracks on the left side. The back of the bolt appears to have hit something as it flew out. The barrel in this action was otherwise in good condition. I would not have wanted to be the one who fired this rifle when it failed.

From the battering on both the bolt and receiver, my guess is that someone was trying to hammer the bolt closed, rather than the bolt blasting back and hitting something, or someone. Just bought a bubba'd 1905 Ross a few months ago. Got a great deal on it because the bolt had been incorrectly assembled, and while it could be inserted in the action, the bolt head kept trying to twist to the left, and jammed hard against the port side of the receiver in exactly the position the receiver bulge is located. If the owner had persisted in trying to bash it closed I'm sure he would've bulged the receiver eventually. Offered him a Mauser that did work (one of Mitchell's masterpieces) for a Ross that didn't, and that's how it ended up coming home with me. I am NOT an expert on the Ross rifle, but I stripped it down, disassembled the bolt, then reassembled things. Found that the bolt can be assembled two ways; one leaves you roughly 1/4" between the face of the bolt body and the back of the bolt head, which results in the head trying to twist, the other leaves roughly 1" between parts, and the completed assembly slides home and locks up smooth as silk. A word regarding the incorrect assembly, while the bolt can be closed by sorta manually holding the bolt head while sliding the body forward, it then locks into its recesses by just the barest margin - I'd estimate only 1/8th or so of the bolt lug surfaces being locked up. Whether it could be fired in this condition I don't know.

Notice that the back of the action, the area which held the take-down button, is broken off. Also, the ejector was violently broken off. These things could only have been broken from the bolt flying back with grate force. They would not have been broken off from the bolt being forced forward.